It would be advantageous for many automatic cooking processes to determine and have at one's disposal a parameter allowing a statement about the progress of the cooking.
From DE 42 31 365 A1, a method is known for baking, roasting or cooking, in which the cooking chamber temperature is controlled to a temperature target value, whereby in multiple successive time intervals, a value of the current cooking chamber temperature, or a value that is linearly-dependent on this current temperature, is determined, and these values are summed. When the sum of the values reaches a predetermined sum target value dependent on the product at the target temperature, or the value that is linearly-dependent on it, a pre-determined heat exposure duration and the reciprocal of the length of a time interval, a signal is produced for terminating the roasting, baking or cooking operation. In this manner, temperature fluctuations in the cooking chamber, as they may occur for example during loading or other disturbing influences can be taken account of during a cooking operation. A disadvantage of this state of the art is that the actual temperature of the cooking product is not used for determination of the cooking, but that merely the cooking chamber temperature is assumed to be a variable corresponding to the cooking product temperature. As a result of this, erroneous evaluation regarding the endpoint of the cooking may occur, specifically for cooking products with large diameter.
EP 0 419 304 A2 discloses a method of cooking of cooking products wherein the pH value or also the core temperature of a cooking product is used for the determination of a pasteurization value (P-value). The cooking appliance should conduct the cooking process in such a way that at the end of the cooking process the desired P-value, that is, the desired degree of freedom from germs in the food, is accurately achieved. After subsequent cooling of the temperature of the cooking product to a value of slightly over 0° C., a food that has a long shelf life can be produced. The P-value is only very indirectly related to how well-cooked the food is.
Also from DE 199 45 021 A1 it is known that a cooking process can be conducted as a function of a pH value or as a function of the hygiene of a cooking product. Furthermore it is described there that the cooking process can also be conducted as a function of the core temperature of a cooking product.
DE 196 09 116 A1 discloses a cooking method in a cooking chamber that is ended when an actual core temperature in a cooking product reaches a target core temperature. When an endpoint of the cooking process is set, the cooking chamber temperature, the circulating flow in the cooking chamber and the humidity level in the cooking chamber are adjusted or altered in such a way that the target core temperature is reached at the predetermined end point in time.
U.S. Pat. No. 4,281,022 discloses a cooking method for the cooking of thin meat in a microwave, in which a degree of cooking of the meat is determined based on the humidity and temperature in the cooking chamber. For this purpose, from the temperature and the humidity in the cooking chamber as well as from the elapsed cooking time, a time tx is calculated that is necessary for reaching a thermal equilibrium. This time tx is used to interrupt the cooking process as soon as a desired degree of cooking is achieved. The relationship between the time tx and the degree of cooking for thin meat is described in U.S. Pat. No. 4,281,022. A disadvantage here is that with the method only a special cooking product can be cooked, and that the cooking product must be cooked from beginning to end until the desired degree of cooking is achieved. Interruption and finishing at a later point in time is not possible with the method.
The disadvantage in the cited state of the art is that hygiene or the P-value and the core temperature of the cooking product are suitable only to a limited extent to determine the how well-cooked a cooking product actually is. Thus, for example, it is generally known that potatoes, even when they have reached a core temperature of almost 100° C. in boiling water, have not yet reached the consistency desired for consumption. Namely, actually it is required that this temperature in the core of the potato pieces be maintained for approximately 3 to 5 minutes in order to make the potatoes ready for consumption. The chemical reactions in which the components of the food are converted in fact require besides temperature a certain time span at which the components of the food can be converted. Such a behavior can be described with the C-value (cooking value) similarly to the P-value. Such a cooking value is known in ecotrophology and can be calculated as follows:
                                          C            BT            UF                    =                                    ∫              St                              t                ′                                      ⁢                                          UF                                                      [                                                                                            T                          i                                                /                                                  (                          t                          )                                                                    -                      BT                                        ]                                    10                                            ⁢                              ⅆ                t                                                    ,        wherein                            (        1        )                            UF=conversion factor,        BT=reference temperature=100° C.,        T(t)=core temperature progression,        St=time at which the starting temperature was exceeded, dependent on the food and        t′=current time.        
A method in which such an integral is determined in the determination of the bacterial load of a food, that is, a P-value, is known from EP 1 317 643 B1. However, there again only the determination of a pasteurization value is disclosed.
A method is known from WO 2004/062372 A2 for the cooking in a cooking chamber of a cooking appliance with a control that has access to the time-dependent and not time-dependent measured data that correlate with the state of the cooking product or of the cooking appliance. The actual development of the cooking process is determined herein with the aid of measured data Z1 of the cooking product I to be cooked, up to a pre-determined time TM before the end of the cooking time TE. Herein the data Z1(TE) at the end of the cooking process TE can be predicted. Herein the core temperature, the browning, the crust formation and also the hygiene of the cooking product are intended to be used as cooking parameters.
Within the framework of a further development, it would be desirable to interrupt the cooking process upon reaching a value for the progress of the cooking set by the client (for example a C-value) and to conclude it at a later time point within the framework of a new cooking process. This would provide a cook in the cafeteria or catering operation with the advantage that a meal could be prepared almost completely at a time when there is no time pressure in the kitchen, and then at a later time point the rest of the cooking could be achieved within a very short period of time without the meal being overcooked.
From WO 01/58214 A1, a method is known for providing a predetermined final preparation of precooked meal portions. Herein using a machine-readable code applied on the packaging, a temperature and a time course are read for a final preparation process, and a final preparation appliance is adjusted correspondingly. The required profile in this case is dependent on the preparation parameters used during the pre-cooking. The final preparation parameters to be used can be determined empirically in preliminary experiments as a function of the pre-preparation state. A disadvantage here is that the client, that is, the cook in a large kitchen or in a catering operation, does not have the possibility of determining himself or herself to what degree the cooking product should be pre-cooked in the first step. Furthermore, the method does not allow to react to a change in the cooking process during pre-cooking in such a way that the final preparation will succeed in any case.
JP 63 128 969 discloses a cooking appliance in which, using a setting device, a start, an interruption and an end of the cooking process can be entered. With the aid of a program, a heating time can be determined at the beginning of a cooking process and a heating time can be determined for the case of reheating. A disadvantage here is that no percentage input can be entered by a client. Also no C-value can be used for the determination of the degree to which a food is cooked, since no core temperature sensor is provided in order to determine an internal cooking parameter in the food. It is not provided either that the food could be finish-cooked at a later time point based on an already-achieved degree of cooking, with the aid of a separate cooking process.
A process for conducting a cooking process in a cooking appliance of the above-mentioned type is known from WO 98/48679, in which, with the aid of the derivative of a cooking parameter with respect to time, the end of a cooking process can be pre-calculated in order to convert the cooking product at a defined time before the end of the cooking process with a subsequent part of the cooking process to an end state. A disadvantage here again is that the cooking process cannot be interrupted, and thus no final cooking process in which the cooking to completion of the cooking product takes place is provided that could be shifted to an arbitrary time point later. Also, input regarding the degree of cooking as a client wish is not provided for.